Many different pump systems are known, for example, impeller pumps, gear pumps, piston pumps, vacuum pumps and the like. A typical pump uses an impeller or a set of blades, which spins to push a flow of fluid in a direction. Less conventional pump designs without impellers are also known, such as peristaltic pumps, magnetic flux pumps or diaphragm pumps that are used in places where the fluid can actually be damaged or the setup space is sufficient. Special features for pumping of red blood cells that avoid damaging the red blood cells are not available in the current pump designs.
U.S. Pat. No. 6,254,355 to Morteza Gharib, one of co-inventors of the present invention, the entire contents of which are incorporated herein by reference, discloses a valveless fluid system based on pinch-off actuation of an elastic tube channel at a location situated asymmetrically with respect to its two ends. Means of pinch-off actuation can be either electromagnetic, pneumatic, mechanical, or the like. A critical condition for the operation of the “hydro-elastic pump” therein is in having the elastic tube attached to other segments that have a different compliance (such as elasticity). This difference in the elastic properties facilitates elastic wave reflection in terms of local or global dynamic change of the tube's cross-section which results in the establishment of a pressure difference across the actuator and thus unidirectional movement of fluid. The intensity and direction of this flow depends on the frequency, duty cycle, and elastic properties of the tube.
The elastic wave reflection of a “hydro-elastic pump” depends on the hydroimpedance of the segments. In the prior art hydro-elastic pump, it was required that the segments to be stiffer either by using a different material or using reinforcement. To overcome the limiting conditions of the prior hydro-elastic pump systems, it is disclosed herein to attach any end member with different hydroimpedance (one special kind of impedances) to the end sections of the hydro-elastic pump for achieving a non-rotary bladeless and valveless pumping operation.
By definition impedance is defined as a combination of resistance and reactance of a system to a flow of alternating current of a single frequency. In this respect, impedance difference between two adjacent systems determines the level of power that will be transmitted or reflected between these two systems. Impedance is a very useful concept in the subject of power delivery. It provides information about the load being driven by the power source. For the output torque of an automobile transmission, the impedance is the output torque divided by the angular velocity that such torque will sustain, For a jet engine, the impedance is the thrust (force) divided by the air-speed that such thrust will sustain, and for a fluid pump, the impedance is the pressure it delivers divided by the volume flow rate that such pressure sustains. In general, an impedance is the ratio of a force or other physical imposition capable of power delivery, to the reaction that such imposition can sustain, where the reaction is defined such that the product of the imposition and sustained reaction has the units of energy per unit time, or power.
For most mechanical systems, a device'impedance varies with the conditions of the situation (such as what slope the automobile is climbing, or the viscosity of the fluid being pumped by the pump), but an electrical impedance will either be a constant value or it will depend on the frequency component of the driving signal.
It is one aspect of the present invention to provide a hydroimpedance pumping system comprising changing a shape of an elastic element in a way which increases a pressure in a first end member of the elastic element more than that in a second end member of the elastic element to move fluid between the first and the second segments based on a pressure differential, wherein the elastic element has end members with different hydroimpedance attached to each end of the elastic element.